Art of stencilization



NOV- 9, 1943 A. M. ALTMAN ETAL 2,333,624

ART 0F sTENcILIzATIoN Filed Sept. 3, 1940 Patented Nov. 9, 1943 ART F STENCILIZATION Ardell M. Altman, Chicago, and Everett J. Shaw,

Western Springs, lll., assignors to A. B.

Dick

Company, Chicago, Ill., a corporation of Illinois Application September 3, 1940, Serial No. 355,142

(Cl. i-127) 2 Claims.

This invention relates to the art of stencilization and more particularly to the correction or other alteration of letters, characters, figures, or other indicia or images, which have been stencilized in duplicating stencils.

Stencil sheets adapted for conversion into duplicating stencils, as now widely used in the art, comprise a support or base sheet coated or impregnated with a suitable mass which is impervious to duplicating ink and which may be removed irom desired areas 0f the sheet, by the process of stencilization, to permit the passage of the ink through such predetermined areas. The base sheet usually consists of-a thin, foraminous, highly permeable material, such as the well-known Japanese yoshino paper. The coating mass consists in general of any suitable material which is impervious to ink, such as fatty or oily material, with suitable modiers integrated or held together by a hlm-forming material, such as cellulose nitrate or gelatin, combined with suitable tempering agents. The stencil coating mass may be compounded with reference to the expected use; for example, to the process by which the stencil is to be stencllized, andas the structure of duplicating stencil sheets and the composition of their coatings are well known in the art, and as such composition forms no part of the present invention, further description thereof is deemed unnecessary.

Stencilization of stencil sheets may be effected in various ways, of which the best known and most commonly used is pressure stencilization, as by the impact of type or by a stylus, in which the impressible coating mass is expresed by the pressure of the instrument used, from the desired areas of the stencil. The present invention has been described by way of example in .connection with a stencil made by this method of stencilization, but it is to be understood that stencilization may be effected in diiierent ways, as by heat, by t chemical or photochemical action, and others, and this invention is not to be limited to the correction or alteration of images which have been stencilized by pressure, but is adapted for use with any duplicating stencil, however made and stencilized.

As now commonly practiced, the correction or aleration of matter stencilized in stencil sheets is effected by the application of correction iiuids, which consist in general of ink-impervious materials dissolved in volatile solvents. To correct or change a character which has been stencilized in a stencil with a typewriter, for example, it is necessary to rst burnish with a suitable blunt instrument that area. of the stencil occupied by the character to be changed, so as to partially close the stencilized opening with stencil-coating mass which was expressed from the area. during the stencilization. After such burnishing, one or more drops or blobs of correction iiuid are applied to the area, as by means of a brush, and are permitted to dry thereon by evaporation of the solvent. The original stencilized opening is thus closed by the material deposited from the correction uid solution and the corrected lcharacter may then be typed in the space which is so lled.

'l'his method of closing stencilized openings by means of .correction fluid is subject to various disadvantages and annoyances. It requires the handling of a sticky liquid andis diiicult, tediousand slow in application. Correction uid solvents are always volatile so that they tend to thicken and dry out before use, and are usually infiammable and a potential fire hazard. Moreover, the relatively thin solvent frequently attacks thel sten' cil coating, penetrates'the stencil sheet at the area of the stencilization to be corrected, and carries through sufficient correction material and dissolved stencil material to permit the stencil sheet to stick to its backing, causing damage to and loss of the stencil sheet, and considerable annoyance.

The principal object of the present invention is to provide improved means for the alteration and correction of duplicating stencils in which the 'above-mentioned disadvantages of correction uid are obviated, and by which superior corrections may be made with greater ease and in much less time. Other objects of the invention will appear from the following description taken in connection with the drawing, which forms a part of this specification, and in which:

Fig. 1 is a plan view of a duplicating stencil showing the method of obliterating or lling in a stencilized opening.

Figs. 2, 3 and 4 are fragmentary sectional views take'n substantially on the lines 2--2, 3 3, and 4-4 Aof Fig. 1 respectively.

Fig. 5 is a view in elevation showing another means of appwing the correction material.

The invention contemplates broadly the closing or filling of stencilized openings in duplicating stencils by solid or semi-solid correction material, to be deposited in the openings at the desired areas by mechanical pressure.4 Thus, the correction material may be in the form of a stick or pencil of suitable ink-impervious material, suiilciently solid to retain its form in handling and in use, but sufficiently soft so that it may be indicates generally a conventional type-impressible stencil sheet having a fibrous base sheet II.

of yoshinoA or similar material impregnated with a soft type or stylus-impressible, ink-impervious coating mass I2 of any Well-known composition. 'I'he coating I2 completely envelops the base sheet II forming clear coated surfaces I3 on each side thereof, the mass on the side from which the coating was applied being somewhat thicker than that on the other side, as is well known.

At Il is shown a type-stencilized opening in the form of the letter B, indicating the manner in which the coating material I2 is expressed by the blow of the type (not shown) from the base sheet, being. pushed aside and piled up at the edges of the opening, as at I6, to expose the fibers II. These fibers, as indicated at II in Fig. 2, are bent down by the impact of the type and some of them may be broken off. but these bared fibers serve to retain the centers of the loop letters in their proper position with respect to the stencil sheet without oiering any material resistance to the passage of ink through the stencilized opening. l

The closing or filling in of such a stencilized opening by means of the plastic correction material of this invention is also indicated in the central portion of Fig. 1 and in Fig. 3, in which I8 indicates the stick or pencil of correction material which is drawn over the stencilized opening, shownl in the form of the letter E, in contact with the upper surface I3 of the stencil, being held in firm contact therewith as will be readily understood. The correction material I9 wiped oif the soft, semi-solid pencil I8 by the pressure of contact is spread in the form of a relatively thin film across the surface I3 of the stencil sheet. The action at the point where the pencil I8 crosses a stencilized opening is clearly shown in. Fig. 3. The ridge or mound oi' extruded stencil coating mass I6 at the edges of the opening is to some extent wiped laterally The correction material of the pencil It may be of any composition which possesses the desired characteristics. It must be impervious to and insoluble in the duplicating ink which is to be used in connection with the stencil to be corrected or altered, and must not affect the stencil coating mass. It should have suflicient mechanical strength and coherence to permit forming in the shape of a rod or pencil and mainta, .ing its form in handling and use. It should b e sufficiently soft and plastic to ow readily and smoothly under the pressure of application into the stencilized openings, and to spread evenly into a thin lm on the surface of the stencil sheet Without scratching or tearing.

Compositions possessing these characteristics may be made from various film-forming substances when properly plasticized and combined with suitable filling material, preferably of an oily or waxy nature, and with lubricants. As an example of a satisfactory correction mass, the following composition has given good results, the proportions being expressed in parts (by weight:

Example I Stearic acid 29 Ethyl cellulose 16 Stearln 15 vPrimex (hydrogenated cotton seed oil) l l2 Oildag (graphited mineral oil) l Castordag (graphited castor oil) and downwardly into the stencilized opening, i

as at 2|, in advance of the correction material I9 which is also forced downwardly by a component of the pressure to ill and close the upper part ofthe stencilized opening.

A filled or obliterated correction of the letter F is shown at the right-hand side of Fig. l and in Fig. 3, the stencilized opening being entirely closed by the correction material I9 and the adjacent area being covered by a thin nlm of this material deposited from the pencil I8 4in the course of application.

Another means of applying the correction material of this invention to close a stencilized opening is illustrated somewhat diagrammatically in Fig. 5, in which the plastic material I9 is extruded from any convenient container, such as a collapsible tube 22 provided with a nozzle 23 and a suitable spreading member 24. By this device a small quantity of the material can be ldeposited from the nozzle 22 in position on the stencil over the -opening to be closed and then spread by the member 23 across said opening. being forced into and :dlling the opening by the In this example, the cellulose ether is an inkimpervious film-forming material dissolved in and plasticized by the stearic acid. The stearin glycerol stearate) is a fatty substance soluble in stearic acid which acts as a modier, distender and softener for the mass, whilethe Primex is a fatty substance which also acts as a modifier for the cellulose binder, and which, as a lubricant, cooperates with the graphited oils to prevent tearing of the stencil. The castordag also acts as a modifier for the ethyl cellulose.

A correction material of somewhat harder composition Well adapted to the alteration of fine y lines, may be compounded as follows:

Triphenyl phosphate i 6 Various materials may be used to form these semi-solid correction masses. Thus'benzyl cellulose may be substituted for ethyl cellulose in the formulae given, and the esters of cellulose, cellulose nitrate and cellulose acetate, may also be used to form satisfactory compositions, as

follows: i

Example III Stearic arid Benzyl cellulose 20 Carnauba 5 Petrolatum l0 Oildag V 20 Tricresyl phosphate.. l0 Example IV Nitrocellulose (6 second) 16 Camphor 20 Castordag 20 Tricresyl phosphate 10 spreading pressure, as will be readily understood. Dibutyl phthalate 20 While the cellulose ethers are preferred as binders, the invention is not limited to cellulosic suitable nlm-forming materials, as: Zein (a vegetable protein derived from corn), Pliowax (a mixture of paraln with Plioliae resin which is rubber reacted with stannic chloride), pohrvlnyl alcohol and the cumarone-indene resins. The following examples are by way of illustration:

Example V Tornesit (20 C. P. s.) -..a 6 Butyl carbltol acetate l Carnauba wax 22 Halowax 36 (Butyl carbitol is a mono butylether of diethyln ene glycol and Halowax is chlorinated naphthaiene).

(Neville resin R6 is a substance known as Nevindene, which is a cumarone-indene lresin.)

In general, any illm forming substance compatible with the stencil coating mass and impervious to the 'duplicating ink, and which is soluble in or miscible with the plasticlzer and capable of producing the proper consistency may be combined with suitable iilling material to form a correction mass in accordance with our invention. I

These binders may be plasticized with a number ot substances which are adapted to keep the mass suiliciently soft and ductile. For example, tributyl citrate, ethyl tartarate, benzyl benzoate, diamyl or dibutyl phthalate, tricresyl phosphate,

` or hydrogenated methyl abietate may be substituted for the triphenyl phosphate of Example II with excellent results. Most of the non-volatile organic esters are suitable as plasticizers for the cellulose ethers and cellulose esters which are preferred as binders for the correction mass, and in general, any substance is suitable as a plasticizer for any particular binder if it forms therewith a compound o the proper density and plasticity, neutral tothe stencil coating and impervious to the ink.

`It. wide range of materials of fatty or waxy nature, which have the desired consistency and Y which are miscible with the other elements of the mass are also suitable as llers and lubricants. Thus, a number of natural and synthetic waxes may be used in place of or together with the stearic acid and stearin of the formulae given, such as Japan wax, bees wax, candelilla wax and carnauba wax. also useful is the material lmown commercially as Stenol, Winch is a mixture of high molecular-weight alcohols, Opal wax which is hydrogenated castor oil, and, in limited quantities, para. Parain, however, not being fully compatible with ethyl or benzyl cellulose must be used in limited quantities,e. g., below 25%. Other materials, such as the product' known commercially as Impervium (made by impervious Products Company of Wyandotte, Michigan) and the micro-crystalline waxes made by the Socony-Vacuum Oil Company of New Yori-r, New York, the chemical composition of which are not hewn to us, are readily incorporated in the mass, and have the advantage of being more compatible with the cellulose ethers. Itwill be understood that any suitable coloring matter may be added to the mass in accordancel with the color of the stencil sheet to be corrected in order to improve by contrast the Example VI Zein 5 Carbitol (mono ethyl ether of diethylene- I glycol) l0 Stearic acid.. 40

' Example VII Pliowax 30 Stearic acid 30 Dark green petrolatum l2 Primex 12 Mineral oil 30 Carnauba wax 90 Example VIII Polyvinyl alcohol (491) l0 RH 539 plasticizer -..-10 Urea 20 Sorbitol laurate l0 Glycerine 5 RH 539 plasticiz'er is ethanol acetamid.

l Example IX Neville resin R6 l 10 Dark green petrolatum 32 Castordag 20 Parailln 8 Carnauba wax 30 visibility of the operation.

What we claim is: 1. A stencil correction material including a cellulose ether, a non-volatile solvent and plas- 

